Folding knife



FIG. 1 is a first perspective view of a folding knife showing my new design;

FIG. 2 is a second perspective view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a back view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a right side view thereof;

FIG. 7 is a top view thereof; and,

FIG. 8 is a bottom view thereof.

The broken lines shown in the drawings depict portions of the folding knife in which the design is embodied that form no part of the claimed design. 

CLAIM The ornamental design for a folding knife, as shown and described. 